The semiconductor die mounting process involves dispensing a small amount of die attach paste to the leadframe bar pad before mounting the individual device to the bar pad. The die attach paste is then cured by heat in order to insure proper adhesion of the device to the leadframe. Die attach pastes presently being used require a cure time in the range of 1-2 hours at a temperature of approximately 250 degree Centigrade.
"Quick Cure" epoxies used as the die attach paste typically out-gases solvents during the cure process. If there is not proper ventilation during the curing period, contaminants from the out-gassed products can be deposited on the surface of the semiconductor device. Reliability of the assembled semiconductor device is adversely affected by any contaminants on the surface of the device.